In recent years, advances in technology, as well as ever evolving tastes in style, have led to substantial changes in the design of automobiles. One of the changes involves the power usage and complexity of the various electrical systems within automobiles, particularly alternative fuel vehicles, such as hybrid, electric, and fuel cell vehicles.
Many electric-powered vehicles require a high primary operating voltage, e.g., 400 volts DC. Typical fuel cells provide less than one volt DC under load. Therefore, a large number of individual fuel cells are often configured or “stacked” in series to provide a fuel cell stack capable of providing the high primary operating voltage required by the vehicle. Power converters, such as direct current-to-direct current (DC/DC) boost converters, are typically used to raise the voltage level of a fuel cell stack up to the level required on the high-voltage bus.
Most vehicles also include one or more auxiliary electrical systems which operate at a lower voltage. For example, most vehicles include one or more auxiliary electrical systems adapted to operate at 12 volts DC. Often, a step-down DC/DC converter (or buck converter) is used to reduce the high-voltage bus voltage down to the operating level required by the auxiliary electrical systems. Although commonplace, the use of additional power converters increases the component cost, size, and complexity of the vehicle electrical system.